1. Field of the Invention
The present invention relates to a temperature control system for a semiconductor manufacturing system, and more particularly, to a temperature control system configured to mix a low temperature heating medium and a high temperature heating medium to supply the heating medium to an electrostatic chuck (ESC) configured to maintain a temperature while supporting a wafer in a chamber in which a semiconductor wafer processing process is performed at a temperature according to a process recipe.
2. Discussion of Related Art
As semiconductor device technology gradually advances, control precision of equipment applied to a semiconductor manufacturing system also becomes important. In particular, vacuum chambers in which various deposition and etching processes of semiconductor substrate materials such as, in particular, silicon wafers, are performed require precise temperature control according to each process recipe.
In recent times, the semiconductor manufacturing system requires stable maintenance of a temperature when the temperature is a desired temperature and rapid variation of a temperature when a temperature in the process recipe is varied. In particular, in recent times, while variation in temperature is required even in a unit step of the process recipe, it is difficult for an external temperature control system to deal with the variation in temperature.
FIG. 1 shows a conventional configuration in which a temperature of an electrostatic chuck 22 in a chamber 20 is uniformly maintained through a chiller 10.
As shown, a heating medium cooled to a constant temperature is provided to the electrostatic chuck 22 in the chamber 20 though the chiller 10 to deal with a predetermined temperature section of the process recipe. In recent times, in a process of manufacturing a fine multi-layer structure, a temperature should be varied even in a specific unit section.
For this, in recent times, the electrostatic chuck 22 may further include a tunable heater such that the temperature in the specific unit section can be controlled by the chamber itself.
FIG. 2 shows the electrostatic chuck 22 having a tunable heater 23. For example, when the heating medium of 20° C., which is set to a target temperature of a specific unit section in the chiller 10, is continuously supplied, if a temperature of 25° C. is needed in the corresponding unit section, the tunable heater 23 is operated to increase the temperature of the electrostatic chuck 22 to 25° C.
Eventually, since such a configuration cannot easily use the external temperature control, which requires a relatively long time to deal with the variation in temperature, and enforces an abrupt variation in temperature through the tunable heater, efficiency in power is substantially degraded. In addition, it is not preferable to install the heater in the electrostatic chuck 22 due to disturbance of radio frequency (RF) power applied to an upper electrode or a shower head 21 in the chamber 20 as shown in FIG. 1.
Accordingly, a temperature control system configured to appropriately mix heating media having different temperatures to rapidly set the temperature of the heating media to a desired target temperature has been proposed.
Since an unstable state upon temperature control continues for a substantially long time due to a substantial thermal capacity of the electrostatic chuck, the heating medium having a sufficient flow rate is required for the temperature control. Accordingly, in recent times, a method of mixing a cooled heating medium and a heated heating medium and providing the mixed heating medium to the electrostatic chuck, a method of appropriately mixing a separately cooled or heated heating medium with a recovered heating medium and supplying the mixed heating medium, or the like, is proposed.
However, in most cases, since the heating medium recovered from the electrostatic chuck is equally supplied to heating medium tanks (reservoirs) of a cooling means and a heating means, power consumption for adjusting the temperature of the recovered heating medium to the set temperatures of the cooling means and the heating means becomes severe. In addition, since a substantial thermal shock is generated when a difference between the temperature of the recovered heating medium and a temperature to be controlled is abruptly increased due to a variation in temperature required by a load, overshoot or undershoot is frequently generated when dealing with the temperature using a conventional control method (for example, proportional-integral-derivative (PID) control), which makes it difficult to control the temperature.
Eventually, a novel type of temperature control system for providing a heating medium having a desired set temperature at a sufficient flow rate, reducing a thermal shock, and minimizing calories for cooling or heating the recovered heating medium is needed.